Posts with compliant junctions

ABSTRACT

Apparatus and methods are described, including a stent configured to be placed in a lumen. The stent includes a generally cylindrical stent body comprising a plurality of struts, and a plurality of antenna posts protruding longitudinally from an end of the stent body. Each of the antenna posts includes a proximal and distal portions, each of which is configured to be generally straight in the absence of any force being applied to the antenna post, and a compliant junction disposed between the proximal and distal portions, the proximal and distal portions being configured to flex with respect to one another about the compliant junction. An antenna is disposed annularly on the distal portions of the antenna posts, such that the antenna posts separate the antenna from the end of the stent body. Other applications are also described.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application claims priority from U.S. Provisional Patent Application 61/900,461 to Dagan, entitled “Wireless endovascular stent-based electrodes,” filed Nov. 6, 2013, which is incorporated herein by reference.

The present application is related to International application PCT/IL2013/050375 (published as WO 13/164829), filed May 2, 2013, entitled “Wireless endovascular stent-based electrodes,” which claims priority from the following US provisional patent applications, which are incorporated herein by reference:

-   -   U.S. Provisional Patent Application 61/641,388 to Dagan, filed         May 2, 2012, entitled “Wireless endovascular stent-based         electrodes;”     -   U.S. Provisional Patent Application 61/714,277 to Dagan, filed         Oct. 16, 2012, entitled, “Wireless endovascular stent-based         electrodes;” and     -   U.S. Provisional Patent Application 61/773,919 to Dagan, filed         Mar. 7, 2013, entitled, “Wireless endovascular stent-based         electrodes.”

The present application is related to U.S. Ser. No. 13/741,154 to Dagan (published as 2014/0180391), which is the US national phase of International application PCT/IL2012/000336 (published as WO 13/035092), filed Sep. 9, 2012, entitled “Wireless endovascular stent-based electrodes,” which claims priority from U.S. Provisional Patent Application 61/532,660 to Dagan, filed Sep. 9, 2011, entitled, “Wireless endovascular stent-based electrodes.”

The present application is related to U.S. Ser. No. 13/210,778 to Dagan (issued as U.S. Pat. No. 8,626,290), filed Aug. 16, 2011, which is a continuation-in-part of U.S. Ser. No. 12/957,799 to Gross (issued as U.S. Pat. No. 8,626,299), filed Dec. 1, 2010, entitled “Thoracic aorta and vagus nerve stimulation,” which is a continuation-in-part of U.S. Ser. No. 12/792,227 to Gross (published as US 2010/0305392), filed Jun. 2, 2010, entitled “Thoracic aorta and vagus nerve stimulation,” which claims the benefit of (a) U.S. Provisional Patent Application 61/183,319 to Reisner, filed Jun. 2, 2009, entitled “Thoracic aorta and vagus nerve stimulation,” and (b) U.S. Provisional Patent Application 61/331,453 to Dagan, filed May 5, 2010, entitled “Thoracic aorta and vagus nerve stimulation.”

All of the above-referenced applications are incorporated herein by reference.

FIELD OF EMBODIMENTS OF THE INVENTION

Some applications of the present invention generally relate to medical apparatus. Specifically, some applications of the present invention relate to stent-based electrodes for placement in a blood vessel.

BACKGROUND

Heart failure is a condition in which a problem with the structure or function of the heart impairs its ability to supply sufficient blood flow to meet the body's needs. The condition impairs quality of life and is a leading cause of hospitalizations and mortality in the Western world. Treatment of heart failure is typically aimed at removal of precipitating causes, prevention of deterioration in cardiac function, and control of congestive state.

Hypertension, or chronic high blood pressure, is an extremely prevalent medical condition, which can lead to strokes, heart attacks, and heart failure. There are a variety of treatments that are available for treating hypertension, including lifestyle changes and medication.

SUMMARY OF EMBODIMENTS

In accordance with some applications of the present invention, a stent is placed within a lumen e.g., a lumen of a blood vessel of a subject, such as the subject's aorta. Typically, the stent defines a stent body, a plurality of antenna posts that protrude from a distal end of the stent body, a plurality of electrode posts that protrude from the distal end of the stent body, and one or more coupling elements for coupling a control capsule to the inner surface of the stent body. Further typically, an antenna is coupled to the stent by being sutured to the antenna posts that protrude from the stent body, a plurality of coiled electrodes are coupled to the stent by being placed upon respective electrode posts, and a control capsule is coupled to stent via the coupling elements. For some applications, a control unit and a transmitter are disposed outside the subject's body. The control unit transmits a signal and/or power toward the stent, via the transmitter. The antenna receives the transmitted signal and/or power, and the control capsule drives the electrodes to drive a current into the blood vessel, in response to the antenna receiving the signal and/or power.

For some applications, the stent includes a generally cylindrical stent body, which includes a generally cylindrical distal section, and a generally cylindrical middle section. The middle section of the stent body includes a plurality of strut rings that are flexibly interconnected to each other, by a plurality of bridges, such as to facilitate curving of the generally cylindrical middle section. The distal section of the stent body, from which the antenna posts protrude, includes at least one distal-section strut ring. The distal and middle sections of the stent body are configured such that, when the stent body is in a radially compressed configuration thereof (for example, when the stent body expands against the inner wall of the subject's blood vessel), the distal-section strut ring exerts an outward radial force that is greater than the outward radial force exerted by each of the middle-section strut rings.

For some applications, each of the antenna posts defines a proximal portion and a distal portion, each of which is configured to be generally straight in the absence of any force being applied to the antenna post. A compliant junction is disposed between the proximal portion and distal portion of the antenna post, and the proximal portion and distal portion are configured to flex with respect to one another about the compliant junction. For some applications, the compliant junction defines a single sinusoidal wave, 1.5 sinusoidal waves, or a different number of sinusoidal waves.

Typically the stent is placed inside the subject's aorta such that the distal end of the stent is in the vicinity of the subject's aortic arch. For some applications, the stent is placed such that the electrodes are disposed between the bifurcation of the aorta with the left subclavian artery and the bifurcation of the aorta with the fifth intercostal artery. For some applications, the control capsule drives the electrodes to drive a current into the subject's aorta, e.g., in order to treat the subject for a condition such as congestive heart failure, diastolic heart failure, and/or hypertension, e.g., as described in U.S. Ser. No. 13/210,778 to Dagan (published as US 2012/0035679), U.S. Ser. No. 12/957,799 to Gross (published as US 2011/0137370), and/or U.S. Ser. No. 12/792,227 to Gross (published as US 2010/0305392), all of which applications are incorporated herein by reference.

It is noted that in the context of the present application, the terms “proximal” and “distal” are to be understood to be with respect to an access point of the stent into the subject's body. Thus, the distal end of the stent is the end of the stent that is further from the access point, and the proximal end of the stent is the end of the stent that is closest to the access point. For applications in which the stent is placed inside the subject's aorta, the term “distal” typically means the portion of the stent or the aorta that is closer to the subject's left ventricle, and the term “proximal” means the portion of the stent or the aorta that is further from the subject's left ventricle.

There is therefore provided, in accordance with some applications of the present invention, apparatus for use with a tubular structure shaped to define a lumen thereof, the apparatus including:

-   -   a stent configured to be placed within the lumen, the stent         including:         -   a generally cylindrical stent body, including a generally             cylindrical distal section, and a generally cylindrical             middle section,             -   the middle section of the stent body including a                 plurality of middle-section strut rings, each of the                 plurality of middle-section strut rings including a                 plurality of middle-section struts, middle-section strut                 rings that are adjacent to one another being flexibly                 interconnected to one another, by a plurality of                 bridges, such as to facilitate curving of the generally                 cylindrical middle section,             -   the distal section of the stent body including at least                 one distal-section strut ring, and             -   the distal and middle sections of the stent body being                 configured such that, when the stent body is in a                 radially compressed configuration thereof, the at least                 one distal-section strut ring exerts an outward radial                 force that is greater than an outward radial force                 exerted by each of the middle-section strut rings; and         -   a plurality of antenna posts protruding longitudinally from             the distal section;     -   and     -   an antenna disposed annularly on the antenna posts.

For some applications:

-   -   the lumen of the tubular structure includes a lumen of a blood         vessel of a subject,     -   the stent is configured to be placed within the lumen of the         blood vessel, and     -   the distal and middle sections of the stent body are configured         such that the at least one distal-section strut ring exerts a         radial force on a wall of the blood vessel that is greater than         a radial force exerted by each of the middle-section strut         rings.

For some applications:

-   -   the lumen of the tubular structure includes a lumen of a blood         vessel of a subject, the blood vessel including a curved portion         shaped to define a curve, an inner wall of the blood vessel at         the curved portion of the blood vessel defining an inner region         that is on an inside of the curve and an outer region that is on         an outside of the curve,     -   the stent is configured to be placed within the lumen of the         blood vessel at the curved portion of the blood vessel, and     -   the middle-section strut rings that are adjacent to one another         are flexibly interconnected to one another, such as to         facilitate a longitudinal expansion of the stent body along the         outer region of the inner wall of the blood vessel that is         greater than a longitudinal expansion along the inner region of         the inner wall of the blood vessel.

For some applications, the middle-section strut rings that are adjacent to one another are flexibly interconnected to one another, such as to facilitate a longitudinal expansion of the stent body along the outer region of the inner wall of the blood vessel, and a longitudinal compression of the stent body along the inner region of the inner wall of the blood vessel.

For some applications:

-   -   the at least one distal-section strut ring includes a plurality         of thickened distal-section struts, each of the thickened         distal-section struts having a greater cross-sectional area than         each of a majority of the middle-section struts, and     -   the at least one distal-section strut ring is configured to         exert a greater outward radial force by virtue of including the         thickened distal-section struts.

For some applications, each of a majority of the thickened distal-section struts is longer than each of a majority of the middle-section struts.

For some applications, the stent body further includes a generally cylindrical proximal section, the proximal section of the stent body including a proximal-section strut ring, the proximal and middle sections of the stent body being configured such that, when the stent body is in the radially compressed configuration thereof, the proximal-section strut ring exerts an outward radial force that is greater than an outward radial force exerted by each of the middle-section strut rings.

For some applications:

-   -   the proximal-section strut ring includes a plurality of         thickened proximal-section struts, each of the thickened         proximal-section struts having a greater cross-sectional area         than each of a majority of the middle-section struts, and     -   the proximal-section strut ring is configured to exert a greater         outward radial force by virtue of including the thickened         proximal-section struts.

For some applications, each of a majority of the thickened proximal-section struts is longer than each of a majority of the middle-section struts.

For some applications, the distal section of the stent body further includes a second distal-section strut ring, the second distal-section strut ring defining a plurality of distally-facing v-shaped strut pairs and the at least one distal-section strut ring defining a plurality of proximally-facing v-shaped strut pairs, and the second distal-section strut ring and the at least one distal-section strut ring are coupled to each other such that each distally-facing v-shaped strut pair of the second distal-section strut ring is coupled to one of the proximally-facing v-shaped strut pair of the at least one distal-section strut ring, such as to form a closed diamond-shaped cell.

For some applications,

-   -   the apparatus further includes a plurality of electrodes;     -   the stent further includes a plurality of electrode posts         coupled to the at least one distal-section strut ring, each of         the electrodes being coupled to the stent by being placed on a         respective electrode post, and         -   the closed-cell arrangement of the distal section is             configured to radially expand within the lumen of the             tubular structure such that:             -   a proximal end of each of the electrodes is brought into                 contact with an inner wall of the tubular structure, and             -   points of contact that the proximal ends of the                 electrodes make with the inner wall generally                 circumscribe a plane, a normal to the plane being                 generally parallel to a local longitudinal axis of the                 structure at the points of contact.

For some applications, the second distal-section strut ring is flexibly coupled to the at least one distal-section strut ring, such as to facilitate curving of the distal section of the stent body.

There is further provided, in accordance with some applications of the present invention, apparatus for use with a tubular structure shaped to define a lumen thereof, the apparatus including:

-   -   a stent configured to be placed in the lumen, the stent         including:         -   a generally cylindrical stent body including a plurality of             struts;         -   at least one electrode post protruding from the stent body;             and         -   a plurality of antenna posts protruding longitudinally from             an end of the stent body, the antenna posts being             longitudinally separated from the electrode post;     -   an antenna disposed annularly on the antenna posts, such that         the antenna posts separate the antenna from the end of the stent         body; and     -   at least one electrode coupled to the stent by being placed on         the electrode post.

For some applications, the lumen of the tubular structure includes a lumen of a blood vessel of a subject, and the stent is configured to be placed inside the lumen of subject's blood vessel.

For some applications, the lumen of the blood vessel includes a lumen of a curved portion of an aorta of the subject, and the stent is configured to be placed inside the lumen of the curved portion of the subject's aorta.

For some applications, the at least one electrode is a coiled electrode.

For some applications, the stent defines one or more coupling elements, the apparatus further including a control capsule that is configured to:

-   -   be coupled to the stent via the coupling elements,     -   receive electrical power from the antenna; and     -   drive a current through the electrodes, using the received         electrical power.

For some applications:

-   -   the at least one electrode post includes a plurality of         electrode posts;     -   the at least one electrode includes a plurality of electrode         that are configured to be coupled to the stent by being placed         on respective electrode posts of the plurality of electrode         posts; and     -   the plurality of electrode posts are disposed around less than         75 percent of a circumference of the stent.

For some applications, the plurality of electrode posts are disposed around less than 50 percent of the circumference of the stent.

For some applications, the plurality of electrode posts are disposed around less than 30 percent of the circumference of the stent.

For some applications, the stent defines one or more coupling elements, the apparatus further including a control capsule that is configured to:

-   -   be coupled to the stent via the coupling elements,     -   receive electrical power from the antenna; and     -   drive a current through the electrodes, using the received         electrical power.

For some applications, the plurality of electrode posts and the coupling elements are disposed around less than 75 percent of the circumference of the stent, and the coupling elements are rotationally displaced with respect to all of the electrode posts defined by the stent.

For some applications, the plurality of electrode posts and the coupling elements are disposed around less than 50 percent of the circumference of the stent.

There is additionally provided, in accordance with some applications of the present invention a method including:

-   -   inserting into a curved portion of an aorta of a subject a         self-expandable stent having a plurality of electrodes, an         antenna, and a control capsule coupled thereto; and     -   causing the stent to become anchored to an inner wall of the         subject's aorta, such that all of the electrodes and the control         capsule are disposed around less than 75 percent of a         circumference of the aorta.

For some applications, causing the stent to become anchored to the inner wall of the subject's aorta, includes causing the stent to become anchored to the inner wall of the aorta such that all of the electrodes and the control capsule are disposed around less than 50 percent of a circumference of the aorta.

For some applications, the method further includes causing the control capsule to receive electrical power from the antenna, and to use the power to drive a current into the aorta via the electrodes, by operating a control unit to transmit RF power to the antenna.

For some applications, causing the stent to become anchored to the inner wall of the subject's aorta includes causing the stent to become anchored to the inner wall of the subject's aorta, such that the control capsule is rotationally displaced with respect to all of the electrodes.

For some applications, causing the stent to become anchored to the inner wall of the subject's aorta includes causing the stent to become anchored to the inner wall of the subject's aorta such that the control capsule is disposed along an outer region of the curved portion of the aorta, at which a curvature of the curved portion of the aorta is less than a curvature of an inner region of the curved portion of the aorta.

There is additionally provided, in accordance with some applications of the present invention, apparatus for use with a tubular structure shaped to define a lumen thereof, the apparatus including:

-   -   a stent configured to be placed in the lumen, the stent         including:         -   a generally cylindrical stent body including a plurality of             struts; and         -   a plurality of antenna posts protruding longitudinally from             an end of the stent body, each of the antenna posts             including:             -   a proximal portion and a distal portion, each of which                 is configured to be generally straight in the absence of                 any force being applied to the antenna post; and             -   a compliant junction disposed between the proximal                 portion and distal portion of the antenna post, the                 proximal portion and distal portion being configured to                 flex with respect to one another about the compliant                 junction; and     -   an antenna disposed annularly on the distal portions of the         antenna posts, such that the antenna posts separate the antenna         from the end of the stent body.

For some applications, the lumen of the tubular structure includes a lumen of a blood vessel of a subject, and the stent is configured to be placed inside the lumen of subject's blood vessel.

For some applications, the compliant junction is shaped to define a single sinusoidal wave.

For some applications, the compliant junction is shaped to define 1.5 sinusoidal waves.

For some applications, the compliant junction is shaped to define 2 or more sinusoidal waves.

For some applications, the lumen of the blood vessel includes a lumen of a curved portion of an aorta of the subject, and the stent is configured to be placed inside the lumen of the curved portion of the subject's aorta.

For some applications, the compliant junction is configured to facilitate flexing of the distal portion of the antenna post with respect to the proximal portion of the antenna post, such that the post at least partially conforms with a curvature of the curved portion of the aorta even at an inner region of the curved portion of the aorta, at which a curvature of the curved portion of the aorta is greater than a curvature of an outer region of the curved portion of the aorta.

For some applications, the apparatus further includes a self-expandable wire that is coupled to the antenna, and that is configured self-expand inside the curved portion of the subject's aorta such as to bring the antenna into contact with an inner wall of the aorta, and the compliant junction is configured to facilitate flexing of the distal portion of the antenna post with respect to the proximal portion of the antenna post, such that the antenna is brought into contact with the inner wall of the aorta even at the inner region of the curved portion of the aorta.

There is further provided, in accordance with some applications of the present invention, apparatus for use with a blood vessel, the apparatus including:

-   -   a stent configured to be placed within the blood vessel, the         stent including:         -   a generally cylindrical stent body including a plurality of             undulating strut rings,             -   a distal-most undulating strut ring including N                 distal-most-ring strut pairs, and             -   a second undulating strut ring being adjacent to the                 distal-most undulating strut ring, the second undulating                 strut ring including N/2 second-ring strut pairs;         -   a plurality of antenna posts protruding longitudinally from             the distal-most undulating strut ring; and         -   a plurality of electrode posts protruding from the             distal-most undulating strut ring; and     -   an antenna disposed annularly on the antenna posts.

For some applications:

-   -   each of the distal-most-ring strut pairs includes two struts         coupled at a respective proximal junction of the distal-most         undulating strut ring,     -   adjacent distal-most-ring strut pairs are coupled to one another         at respective distal junctions of the distal-most undulating         strut ring,     -   each strut of each second-ring strut pair is coupled to a         respective proximal junction of the distal-most undulating strut         ring, such as to define N/2 closed-cell arrangements,     -   the plurality of antenna posts protrude longitudinally from         respective distal junctions of the distal-most undulating strut         ring, and     -   the plurality of electrode posts protrude from respective         proximal junctions of the distal-most undulating strut ring.

For some applications, the apparatus further includes a plurality of electrodes, each electrode being coupled to the stent by being placed on one of the electrode posts.

For some applications, each of the electrode posts protrudes from a respective one of a plurality of consecutive proximal junctions.

For some applications:

-   -   a number of antenna posts is N/2, and     -   each of the antenna posts protrudes from a respective distal         junction such that alternate distal junctions are coupled to an         antenna post.

For some applications, N is an even integer between 9 and 15.

For some applications, N is 12.

The present invention will be more fully understood from the following detailed description of embodiments thereof, taken together with the drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a stent having electrodes and an antenna disposed thereon, the stent having been placed inside a subject's aorta, in accordance with some applications of the present invention;

FIGS. 2A-B are schematic three-dimensional illustrations showing respective views of a self-expandable stent in its expanded configuration, in accordance with some applications of the present invention;

FIG. 3 is a schematic illustration showing the structure of a stent for placing inside a blood vessel, in accordance with some applications of the present invention;

FIG. 4 is a schematic illustration of an antenna post for supporting an antenna, in accordance with some applications of the present invention; and

FIG. 5 is a schematic illustration showing the structure of a stent for placing inside a blood vessel, in accordance with some applications of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference is now made to FIG. 1, which is a schematic illustration of a self-expandable stent 20 placed inside a tubular structure, at least one electrode 22 (FIGS. 2A-B), and typically, a plurality of electrodes, being disposed on the stent, in accordance with some applications of the present invention. For some applications, stent 20 is placed inside a subject's blood vessel, stent 20 typically being placed inside the subject's aorta 23, as shown. Reference is also made to FIGS. 2A-B, which are schematic illustrations of the stent in its expanded configuration, and in the absence of the subject's anatomy, in accordance with some applications of the present invention. It is noted that the stent as depicted in FIG. 1 is illustrative, and that the appearance of the stent is typically as shown and described with reference to FIGS. 2A-B, and FIGS. 3-5.

Typically, a control unit 24 and a transmitter 26 are disposed outside the subject's body, as shown in FIG. 1. For some applications (not shown), the control unit and/or the transmitter are implanted (e.g., subcutaneously implanted) inside the subject's body. Typically, an antenna 28 and a control capsule 30 (FIGS. 2A-B) are coupled to stent 20. Control unit 24 transmits a signal and/or power toward stent 20, via transmitter 26. Antenna 28 receives the transmitted signal and/or power, and control capsule 30 drives the electrodes to drive a current into the blood vessel, in response to the antenna receiving the signal. For some applications, control capsule 30 transmits data to control unit 24 by transmitting a signal from antenna 28 toward transmitter 26. Thus, for some applications, antenna 28 may also act as a transmitter, and transmitter 26 may also act as a receiver. Typically, transmitter 26 and antenna 28 communicate with one another via inductive coupling. For some applications, control unit 24 is programmable using a computer. For example, a user (such as a physician) may use a computer (not shown) to program control unit 24, using a standard communication protocol, such as Bluetooth®, to facilitate communication between the computer and control unit 24.

Typically, electrodes 22 are placed in contact with an aortic site, which is as described in U.S. Ser. No. 13/210,778 to Dagan (issued as U.S. Pat. No. 8,626,290), U.S. Ser. No. 12/957,799 to Gross (issued as U.S. Pat. No. 8,626,299), and/or U.S. Ser. No. 12/792,227 to Gross (published as US 2010/0305392), all of which applications are incorporated herein by reference. The aortic site is typically between the bifurcation of the aorta with the left subclavian artery and the bifurcation of the aorta with the fifth intercostal artery. Further typically, the aortic site is between the bifurcation of the aorta with the left subclavian artery and the bifurcation of the aorta with the fourth intercostal artery, e.g., between the bifurcation of the aorta with the left subclavian artery and the bifurcation of the aorta with the first intercostal artery. For some applications, the aortic site is between the bifurcations of the aorta with the first and fifth intercostal arteries.

Typically, a current is driven into the subject's aorta, e.g., in order to treat the subject for a condition such as congestive heart failure, diastolic heart failure, and/or hypertension, e.g., as described in U.S. Ser. No. 13/210,778 to Dagan (issued as U.S. Pat. No. 8,626,290), U.S. Ser. No. 12/957,799 to Gross (issued as U.S. Pat. No. 8,626,299), and/or U.S. Ser. No. 12/792,227 to Gross (published as US 2010/0305392), all of which applications are incorporated herein by reference. For some applications, stent 20 is cut from a nitinol tube (or a tube made from a different material, such as stainless steel) having a wall thickness of more than 0.2 mm (e.g., more than 0.4 mm), and/or less than 0.7 mm (e.g., less than 0.6 mm). For some applications, the length of the stent is more than 25 mm (e.g., more than 30 mm), and/or less than 100 mm (e.g., less than 40 mm). The stent is shape set to a desired expanded configuration of the stent, using techniques that are known in the art. For some applications, the stent is shape set such that in its expanded configuration (i.e., in the absence of any forces acting on the stent), the stent has a maximum outer diameter of more than 10 mm (e.g., more than 15 mm), and/or less than 60 mm (e.g., less than 50 mm). The stent is typically configured such that, upon being deployed in its expanded configuration inside the subject's aorta, the stent anchors itself within the aorta by at least the ends of the stent body (and, typically, the entire stent body) expanding such as to contact the inner wall of the aorta. Furthermore, the stent is typically configured such that, upon being deployed in its expanded configuration inside the subject's aorta, the stent maintains electrodes 22 in contact with the aortic site, and the stent maintains antenna 28 in an open configuration, as described in further detail hereinbelow.

Stent 20 is typically configured to be placed inside the blood vessel (e.g., the aorta) percutaneously (e.g., transfemorally) using a delivery system, e.g., using a 12 Fr-20 Fr catheter (e.g., a 16 Fr catheter). In order to facilitate the percutaneous placement of the stent into the blood vessel (e.g., the aorta), using the catheter, the stent is crimped. Typically, the stent has a crimped profile of less than 20 Fr (e.g., 18 Fr or less), and/or more than 8 Fr (e.g., 10 Fr or more). Typically, stent 20 defines coupling elements 31 at a proximal end of the stent. For some applications, the coupling elements are disposed at a location along the length of the stent other than the proximal end of the stent. During insertion of the stent via the catheter, the delivery system holds the stent in place with respect to the catheter using the coupling elements. In order to place the stent inside the blood vessel at a deployment location, the catheter is retracted at the deployment location, such that the stent is released from the catheter. The stent becomes anchored to the blood vessel via radial expansion of the stent against the inner wall of the blood vessel. Subsequently, the coupling elements are decoupled from the delivery system, and the catheter is withdrawn from the blood vessel.

For some applications, upon being placed inside the blood vessel, the stent is partially deployed by retracting the catheter with respect to the stent, such that (a) electrodes 22 contact the wall of the blood vessel at a given location within the blood vessel, and (b) a proximal portion of the stent is disposed inside the catheter, such that the stent may be retrieved into the catheter. For some applications, the response of the subject to electrical stimulation of the blood vessel at the current location of the electrodes within the blood vessel is determined. In response thereto, the stent is (a) fully deployed at the current location of the stent, (b) retrieved into the catheter and redeployed at a different location within the blood vessel, or (c) retrieved into the catheter and removed from the subject's body (e.g., if the subject does not respond in a suitable manner to electrical stimulation of the blood vessel at any location at which the stent is deployed). Alternatively or additionally, prior to stent 20 being placed inside the blood vessel (e.g., inside the aorta), a mapping device is placed inside the blood vessel, the mapping device including stimulation electrodes. The subject's blood vessel is electrically stimulated at a plurality of stimulation sites using the stimulation electrodes of the mapping device, and the subject's response to electrical simulation at respective sites within the blood vessel is monitored. Subsequently, the mapping device is retrieved from the blood vessel, and stent 20 is placed inside the blood vessel. The location at which to deploy stent 20 within the blood vessel is determined, in response to the monitoring of the subject's responses to the stimulation at the respective sites using the mapping device.

Typically, the compliance of stent 20 is such that pulsation of the blood vessel is substantially maintained upon the stent being deployed inside the blood vessel. Further typically, the stent and components coupled thereto (such as control capsule 30) are shaped such as to substantially maintain blood flow through the blood vessel upon deployment of the stent inside the blood vessel.

As shown in FIG. 2A, stent 20 typically defines one or more coupling elements 40 for facilitating coupling of control capsule 30 to the stent. For some applications, as shown, the stent defines rings that define holes. The control capsule is coupled to the stent by inserting protrusions that protrude from the back of the control capsule into the rings. As shown, the control capsule is typically configured to be coupled to the stent such that the control capsule is disposed on the inner surface of the stent. For some applications, a length of the control capsule is more than 10 mm, less than 30 mm (e.g., less than 25 mm), and/or 10-30 mm (e.g., 10-25 mm). Typically, the width and depth of the capsule are each greater than 1 mm (e.g., greater than 2 mm), less than 5 mm (e.g., less than 3 mm), and/or 1-5 mm (e.g., 2-3 mm).

Typically, at least one electrode 22 is configured to be coupled to stent 20. For some applications, electrode 22 is coiled and is coupled to stent 20 by being placed upon an electrode post 42 that protrudes from the body of stent 20. The electrode is typically disposed on an electrode construction that is configured such that, when the electrode construction is placed on the electrode post, electrode 22 is electrically isolated from the antenna and from the stent body, for example as described with reference to FIGS. 8A-B of US 2014/0180391 to Dagan, which is incorporated herein by reference. For some applications, electrode post 42 is shaped to define protrusions 44, such as to prevent the electrode construction from sliding toward the stent body, when the electrode construction is coupled to the electrode post. Typically, at least 2 electrodes (e.g., at least 3 electrodes), and/or less than 12 electrodes (e.g., less than 6 electrodes) are coupled to stent 20, respective electrodes being placed upon respective electrode posts that protrude from the stent body. For example, 3-5 electrodes (e.g., 4 electrodes) may be coupled to stent 20, respective electrodes being placed upon respective electrode posts that protrude from the stent body.

Typically, antenna 28 is made of a metal wire, e.g., a gold wire. In order for transmitter 26 to communicate with antenna 28 via inductive coupling, it is typically desirable that the antenna become fully expanded inside the blood vessel, such that the antenna is in contact with the inner wall of the blood vessel. For some applications, in order to facilitate expansion of the antenna inside the subject's blood vessel, nitinol wire 29 is coupled to the gold wire, and the nitinol wire is shape set in a desired expanded configuration of the antenna. The distal end of the delivery catheter that is used to deliver stent 20 is retracted at the deployment location of the stent, as described hereinabove. The retraction of the delivery catheter causes the nitinol wire to self-expand inside the subject's blood vessel, and due to the coupling of the nitinol wire to the gold wire, the nitinol wire causes the antenna to expand into the desired expanded configuration (e.g., such that the antenna is in contact with the inner wall of the blood vessel). Typically, the antenna includes a plurality of turns of the gold wire. For example, the antenna may include more than 2 turns, and/or less than 12 turns, e.g. 2-12 turns or 2-6 turns. For some applications, the antenna includes 6 turns of the gold wire, the six turns of wire being separated into 3 levels that are separated from another, as shown. For some applications, the antenna wires are shaped in a waved configuration, as shown.

Antenna 28 and nitinol wire 29 are typically coupled to stent 20 by being sutured to antenna posts 46, which protrude from the stent body of stent 20 separately from electrode posts 42. As described hereinabove, for some applications, antenna 28 is used to receive electrical power for powering the control capsule 30 to drive a current via electrodes 22. Typically, the antenna receives power via inductive coupling, e.g., by transmitter 26 (shown in FIG. 1), or a different transmitter, transmitting RF energy toward antenna 28, such as to generate a magnetic field through the antenna. The magnetic field passing through antenna 28 generates an inductive current through antenna 28. The current through antenna 28 in turn generates a magnetic field, which can generate an inductive current through the body of stent 20, which may interfere with the antenna current, and reduce the efficiency of the electrical powering of the control capsule. The antenna posts are configured such that, when the antenna is sutured to the antenna posts, the antenna is separated from the distal end of the stent body. For some applications, by separating the antenna from the distal end of the stent body, the posts reduce the strength of the inductive current that is generated in the stent body, thereby increasing the efficiency of the electrical powering of the control capsule, via the inductive current that is generated through the antenna. For some applications, a length L (FIG. 3) of each of antenna posts 46 is less than 20 mm, e.g., less than 15 mm, and/or greater than 1 mm, e.g., greater than 5 mm.

As described hereinabove, stent 20 defines electrode posts 42, which are separate from antenna posts 46. The electrode posts and the antenna posts are configured such as to provide a longitudinal separation between the electrodes and the antenna. In this manner, electrical interference between the antenna and the electrodes is reduced relative to if, for example, the electrodes were to be placed upon the antenna posts.

Typically, antenna 28 is wiredly coupled to control capsule 30 (wires not shown), and the control capsule is powered using the inductive current of the antenna. For some applications, the inductive current of the antenna is the only source of power for the control capsule. The control capsule is typically configured to drive a current into the blood vessel via electrode 22 (e.g., to stimulate the blood vessel), and/or to receive an electrical parameter of the blood vessel via the electrode. Typically, the control capsule is wiredly coupled to electrode 22 (wires not shown), and, in cases in which there is more than one electrode 22, the control capsule is wiredly coupled to each of electrodes 22. For some applications, stent 20 is shaped to define a wire holder 48 that is configured to hold in place, with respect to the stent body, the wires that couple the antenna and the electrode(s) to the control capsule, by the wires being threaded through slots defined by the wire holder.

As described hereinabove, typically at least 2 electrodes 22 (e.g., at least 3 electrodes), and/or less than 12 electrodes (e.g., less than 6 electrodes) are coupled to stent 20, respective electrodes being placed upon respective electrode posts that protrude from the stent body. For example, 3-5 electrodes (e.g., 4 electrodes) are coupled to stent 20, respective electrodes being placed upon respective electrode posts that protrude from the stent body. For some applications, electrodes 22 are disposed evenly around the circumference of stent 20. Typically, as shown in FIGS. 2A-B, electrodes 22 are not disposed evenly around the circumference of stent 20. As shown in FIG. 1, stent 20 is typically placed inside the subject's aorta, in a curved portion of the aorta that is in the vicinity of the aortic arch. The curved portion defines an inner region 25 of the curve at which the curvature of the curved portion is greater, and an outer region 27 of the curve at which the curvature of the curved portion is lower. In experiments conducted by inventors of the present application, stimulation of the aorta was applied to 12 human subjects at aortic sites, as described hereinabove. The stimulation was applied at respective circumferential locations of the aorta at the aortic site, and the subjects' responses were measured. If one's perspective is looking along the descending aorta from the bottom of the ascending aorta toward the aortic arch, and the center of the outer region of the curved portion (i.e., the location at which the curvature of the curved portion of the aorta is at a minimum) is designated the 12 o'clock position, it was determined that the subjects typically responded best to stimulation at the aortic site at circumferential locations between the 7 o'clock and 12 o'clock positions.

Therefore, typically, 3-5 electrodes (e.g., 4 electrodes) are coupled to stent 20 such that when the stent is placed inside the subject's aorta, the electrodes are placed in contact with the aorta at an aortic site as described hereinabove, and at circumferential locations that are between the 5 o'clock and the 1 o'clock positions (e.g., between the 7 o'clock and 12 o'clock positions). For some applications, stent 20 defines 3-5 electrode posts 42 (e.g., 4 electrode posts), the electrode posts being disposed around less than 75 percent, e.g., less than 50 percent, or less than 30 percent of the circumference of stent 20, such that the electrodes are brought into contact with a corresponding portion of the circumference of the aorta. In this manner, using a given amount of power, the efficiency of driving the current into the aortic site, in terms of having a desired effect on the subject, is greater than if the current were to be applied evenly around the full circumference of the aorta at the aortic site.

In embodiments in which stent 20 is placed within a curved portion of the aorta, it is typically desirable that the control capsule (which has a flat surface) be placed toward the outside of the curve, where the curvature of the inner wall of the aorta is lower than that of the inner wall of the aorta toward the inside of the curve. Therefore, the one or more coupling elements 40, to which the control capsule is coupled, are typically disposed such that when the stent is deployed inside the aorta, the coupling elements (and therefore, the control capsule) are disposed between the 9 o'clock and 3 o'clock positions (e.g., between the 10 o'clock and 2 o'clock positions), and the electrode posts and the electrodes are disposed between the 5 o'clock and the 1 o'clock positions (e.g., between the 7 o'clock and 12 o'clock positions). Further typically, all of the electrode posts, as well as the one or more coupling elements 40 (and therefore, the control capsule) are disposed around less than 75 percent of the circumference of the stent, e.g., around less than 50 percent of the circumference of the stent. In addition, when looking along the stent from the proximal end of the stent (i.e., the opposite end of the stent from the end from which the antenna posts protrude) to the distal end of the stent (i.e., the end of the stent from the end from which the antenna posts protrude), the one or more coupling elements 40 (and therefore, the control capsule) are disposed at a clockwise rotational displacement (e.g., a clockwise rotational displacement of less than 30 degrees) from all of the electrode posts, as shown.

For some applications (not shown), electrode posts 42 are evenly spaced around the full circumference of the distal end of stent 20, as described hereinabove.

Reference is now made to FIG. 3, which is a schematic illustration of stent 20, in accordance with some applications of the present invention. FIG. 3 shows a flattened profile of the stent, which depicts (for illustrative purposes) how the stent would appear if a longitudinal incision were to be made along the length of the stent at a given circumferential location of the stent, and the stent were to then be laid out flat upon a surface. Stent 20, as shown in FIG. 3, comprises a generally cylindrical stent body 52 comprising a generally cylindrical proximal section 54, a generally cylindrical distal section 56, and a generally cylindrical middle section 58. In the context of the present application, the term “section” should be understood as referring to a cylindrical portion of stent 20. As further described hereinbelow, a “section” typically comprises one or more strut rings, i.e., ring-shaped formations of struts, along with other elements, e.g., coupling elements such as bridges or flexible junctions.

Middle section 58 comprises a plurality of middle-section strut rings 60, each middle-section strut ring 60 comprising a plurality of middle-section struts 62. Middle-section strut rings 60 that are adjacent to one another are flexibly interconnected to one another by a plurality of bridges 64. The flexible interconnection of adjacent rings 60 facilitates curving of middle section 58, which in turn facilitates placement of the middle section within a curved portion of the blood vessel, e.g., at an aortic site in the vicinity of a subject's aortic arch, as described herein.

Distal section 56 comprises at least one distal-section strut ring 66. Distal section 56 and middle section 58 are configured such that, when stent body 52 is in a radially compressed configuration thereof, distal-section strut ring 66 exerts an outward radial force that is greater than an outward radial force exerted by each of the middle-section strut rings 60. For example, when placed within a blood vessel, the wall of the blood vessel radially compresses stent body 52, and distal-section strut ring 66 exerts a radial force on the wall that is greater than the radial force exerted by each of middle-section strut rings 60. The greater radial force exerted by distal-section strut ring 66 helps distal section 56 anchor stent 20 in place, i.e., it helps distal section 56 generally remain in place at a desired position within the blood vessel. Furthermore, the greater radial force exerted by distal-section strut ring 66 helps distal section 56 maintain electrodes 22 in contact with the inner wall of the blood vessel, and maintain antenna 28 in an open configuration.

For some applications, as shown in FIG. 3, distal-section strut ring 66 comprises a plurality of thickened distal-section struts 68, each thickened strut 68 having a greater cross-sectional area than each of a majority of middle-section struts 62. (In the example shown in FIG. 3, each thickened strut 68 has a greater cross-sectional area than each of middle-section struts 62.) In such applications, distal-section strut ring 66 is configured to exert a greater outward radial force by virtue of distal-section struts 68 being thickened. For some applications, also as shown in FIG. 3, each of a majority of thickened distal-section struts 68 is longer than each of a majority of middle-section struts 62. (In the example shown in FIG. 3, each thickened strut 68 is longer than each of middle-section struts 62.) Typically, the increased length of thickened struts 68 helps reduce strain on distal section 56 that may result from the increased cross-sectional area of thickened struts 68.

Stent 20 further comprises a plurality of antenna posts 46 protruding longitudinally from distal section 56, the antenna posts being generally as described hereinabove. The apparatus typically includes antenna 28 (not shown in FIG. 3) disposed annularly on antenna posts 46, the antenna typically being made of gold and being supported by nitinol wire 29, as described hereinabove.

With reference again made to FIG. 1, stent 20 is configured to be placed within a curved portion of a blood vessel. For example, for some applications, stent 20 is configured to be placed inside the subject's aorta, at an aortic site in the vicinity of the subject's aortic arch. The aortic site is typically between the bifurcation of the aorta with the left subclavian artery and the bifurcation of the aorta with the fifth intercostal artery. Further typically, the aortic site is between the bifurcation of the aorta with the left subclavian artery and the bifurcation of the aorta with the fourth intercostal artery, e.g., between the bifurcation of the aorta with the left subclavian artery and the bifurcation of the aorta with the first intercostal artery. For some applications, the aortic site is between the bifurcations of the aorta with the first and fifth intercostal arteries.

As described hereinabove, the inner wall of the aorta at the aortic site defines an inner region 25 that is on the inside of the curve and an outer region 27 that is on the outside of the curve. The flexible interconnection of adjacent middle-section strut rings 60, described above with reference to FIG. 3, facilitates a longitudinal expansion of stent body 52 along outer region 27 that is greater than a longitudinal expansion along inner region 25. For some applications, the flexible interconnection of adjacent middle-section strut rings 60 facilitates a longitudinal expansion of stent body 52 along outer region 27, and a longitudinal compression of stent body 52 along inner region 25.

For some applications, as shown in FIG. 3, proximal section 54 comprises a proximal-section strut ring 70. Proximal section 54 and middle section 58 are configured such that, when stent body 52 is in the radially compressed configuration thereof (e.g., inside the blood vessel, as described hereinabove), proximal-section strut ring 70 exerts an outward radial force that is greater than an outward radial force exerted by each of middle-section strut rings 60. The greater outward radial force helps proximal section 54 anchor stent 20 in place, as described above with respect to distal section 56. For some applications, as shown in FIG. 3, proximal-section strut ring 70 comprises a plurality of thickened proximal-section struts 72, each thickened strut 72 having a greater cross-sectional area than each of a majority of middle-section struts 62. (In the example shown in FIG. 3, each thickened strut 72 has a greater cross-sectional area than each one of middle-section struts 62.) In such applications, proximal-section strut ring 70 is configured to exert a greater outward radial force by virtue of proximal-section struts 72 being thickened. For some applications, as shown in FIG. 3, each of a majority of thickened proximal-section struts 72 is longer than each of a majority of middle-section struts 62. (In the example shown in FIG. 3, each thickened strut 72 is longer than each of middle-section struts 62.) Typically, the increased length of thickened struts 72 helps reduce strain on proximal section 54 that may result from the increased cross-sectional area of thickened struts 72.

For some applications, as shown in FIG. 3, distal section 56 further comprises second distal-section strut ring 74, ring 74 being coupled to ring 66 in a closed-cell arrangement, i.e., such that each distally-facing v-shaped strut pair 76 of ring 74 is coupled to a proximally-facing v-shaped strut pair of ring 66, such as to form a closed diamond-shaped cell.

For some applications, stent 20 further comprises a plurality of electrode posts 42 coupled to distal-section strut ring 66, the electrode posts being generally as described hereinabove. The apparatus further comprises a plurality of electrodes 22 (FIGS. 2A-B), each of which is coupled to stent 20 by being placed on a respective electrode post 42, as described hereinabove. For some applications, stent 20 is placed within a curved blood vessel, e.g., near the aortic arch, and electrodes 22 are placed in contact with an aortic site in the vicinity of the aortic arch, e.g., as described hereinabove, and/or as described in U.S. Ser. No. 13/210,778 to Dagan (published as US 2012/0035679), U.S. Ser. No. 12/957,799 to Gross (published as US 2011/0137370), and/or U.S. Ser. No. 12/792,227 to Gross (published as US 2010/0305392), all of which applications are incorporated herein by reference. In such applications, it is typically preferred that electrodes 22 along the inside of the curve not move ahead of electrodes 22 along the outside of the curve (or vice-versa), such as to apply the electrodes to the blood vessel at approximately the same longitudinal position. The closed-cell arrangement of distal section 56 typically helps bring the electrodes into contact with the inner wall of the blood vessel at approximately the same longitudinal position, at least due to reduced flexibility of the closed-cell arrangement relative to open-cell arrangements. (Middle section 58, for example, comprises open-cell arrangements of strut pairs 78, in which it is not the case that every distally-facing v-shaped strut pair is coupled to a proximally-facing v-shaped strut pair of an adjacent ring, such as to form a closed diamond-shaped cell, as described hereinbelow. Therefore, the middle section is typically more flexible than distal section 56.) For example, the proximal end of each of the electrodes is brought into contact with the inner wall of the blood vessel, and points of contact that the proximal ends of the electrodes make with the inner wall generally circumscribe a plane, a normal to the plane being generally parallel to a local longitudinal axis of the structure at the points of contact.

For some applications, as shown in FIG. 3, second distal-section strut ring 74 is flexibly coupled to distal-section strut ring 66, such as to facilitate curving of distal section 56. For example, FIG. 3 show rings 66 and 74 coupled by a plurality of flexible junctions 80, which for some applications comprise springs. Junctions 80 facilitate movement of rings 66 and 74 with respect to one another, the movement including movement that is generally transverse to the longitudinal axis of the stent and the blood vessel. The flexible coupling of rings 66 and 74 facilitates the placement of distal section 56 in areas of relatively high curvature, e.g., within the aorta, near the aortic arch.

For some applications, each of antenna posts 46 comprises a proximal portion 82, a distal portion 84, and a compliant junction 85. Proximal portion 82 and distal portion 84 are configured to be generally straight in the absence of any force being applied to antenna post 46. Proximal portion 82 and distal portion 84 are further configured to flex about junction 85, with respect to one another. The flexibility of antenna posts 46 facilitates the placement of the antenna posts in a portion of a blood vessel having relatively high curvature, e.g., within the aorta, near the aortic arch, as described herein. For some applications, compliant junction 85 is shaped to define between 0.5 and 3 sinusoidal waves. For example, the compliant junction may be shaped to define a single sinusoidal wave, as shown in FIG. 3. Alternatively, the compliant junction may be shaped to define 1.5 sinusoidal waves, as described hereinbelow with reference to FIG. 4, or a different number of sinusoidal waves (e.g., 2 waves or 3 waves). For some applications, compliant junction 85 has a different shape that is such as to facilitate flexing of portions 82 and 84 with respect to one another.

As described above, antenna 28 (FIGS. 2A-B) is disposed annularly on the antenna posts, such that the antenna posts separate antenna 28 from the end of stent body 52. In order for transmitter 26 to communicate with antenna 28 via inductive coupling, it is typically desirable that the antenna become fully expanded inside the blood vessel, such that the antenna is in contact with the inner wall of the blood vessel. Nitinol wire 29, which is coupled to the antenna, typically self-expands inside the subject's blood vessel, and causes the gold antenna to expand such that the antenna is in contact with the inner wall of the blood vessel. For some applications, by facilitating flexing of distal portion 84 of post 46 with respect to proximal portion 82 of the post, junction 85 facilitates bending of the distal portion of the post radially outwardly from the outer surface of the stent body. In this manner, even posts that are disposed on inner region 25 (FIG. 1) of the curved portion of the aorta are able to bend such as to at least partially conform with the curvature of the aorta. Since the antenna is coupled (typically, via suturing) to the distal portions of the posts, the bending of the posts is typically such as to facilitate full expansion of the antenna, such that the antenna is brought into contact with the inner wall of the aorta even at inner region 25 of the curved portion of the aorta.

For some applications, at least some of strut rings 60 and 70 are shaped to define an undulating strut ring. For example, FIG. 3 shows each of strut rings 60 and 70 shaped to define an undulating strut ring. Each undulating strut ring comprises a plurality of strut pairs, e.g., a plurality of v-shaped strut pairs 78. Each pair 78 comprises two struts 62 coupled to one another at a respective proximal junction 86 of the undulating ring. Typically, a plurality of bridges 64 couple the undulating rows to each other and to ring 74. For some applications, each bridge 64 couples a first strut pair 78 in a first ring to a second strut pair 78 in an adjacent ring. For example, FIG. 3 shows each bridge 64 coupling a proximal junction 86 of a first strut pair 78 in a first ring to a proximal junction 86 of a second strut pair 78 in an adjacent ring. Each bridge 64 is coupled to the proximal side of the junction of the more distal ring, and to the distal side of the junction of the more proximal ring.

Typically, each proximal junction 86 of a given ring 60 is coupled directly, via a bridge 64, to a proximal junction of exactly one of (a) a strut pair belonging to an adjacent ring that is disposed proximally to the given ring, and (b) a strut pair belonging to an adjacent ring that is disposed distally to the given ring. Such a configuration typically increases flexibility of stent 20, relative to a configuration (not shown) in which one or more proximal junctions 86 are coupled directly to proximal junctions of both (a) and (b). Further typically, as shown in FIG. 3, bridges 64 are disposed between alternating opposing pairs of proximal junctions of a given pair of adjacent rings. Thus, between each pair of bridges 64 there is an opposing pair of proximal junctions to which no bridge is coupled. In this manner, middle section 58 comprises open-cell arrangements of strut pairs 78, in which it is not the case that every distally-facing v-shaped strut pair is coupled to a proximally-facing v-shaped strut pair of an adjacent ring, such as to form a closed diamond-shaped cell.

For some applications, as shown, at least some of bridges 64 comprise a portion 88 that is generally straight and rigid. As stent 20 is longitudinally stretched, portions 88 of bridges 64 facilitate the transmission of tensile force to the respective strut pairs 78 to which they are coupled, and the strut pairs deform in response to the tensile force. For example, for some applications, portions 88 of bridges 64 are configured to at least partially invert v-shaped pairs 78 (i.e., at least partially increase the angle define by the v-shaped pairs), upon stent 20 being longitudinally stretched.

For some applications, at least some of bridges 64 comprise a flexible portion 90, e.g., a sinusoidally-shaped flexible portion 90. As stent 20 is longitudinally stretched, some tensile force may be transferred to flexible portions 90 of bridges 64, and the flexible portions may deform, e.g., stretch, in response thereto. For some applications, flexible portions 90 facilitate the placement of stent 20 in areas of relatively high curvature, e.g., near the aortic arch (e.g., as described hereinabove), by facilitating curving of stent 20.

Reference is now made to FIG. 4, which is a schematic illustration of antenna post 46, in accordance with some applications of the present invention. As described hereinabove, for some applications, each of antenna posts 46 comprises a proximal portion 82, a distal portion 84, and a compliant junction 85. As described hereinabove, typically the compliant junction is shaped to define between 0.5 and 3 sinusoidal waves. For example, the compliant junction may be shaped to define a single sinusoidal wave, as shown in FIG. 3. Alternatively, the compliant junction may be shaped to define 1.5 sinusoidal waves, as shown in FIG. 4. For some applications, shaping the junction to define 1.5 sinusoidal waves increases the compliance of the junction relative to if the junction were to define a single sinusoidal wave, as shown in FIG. 3. For some applications, the compliant junction is shaped to define a different number of sinusoidal waves, e.g., 2 or 3 waves. For some applications, compliant junction 85 has a different shape that is such as to facilitate flexing of portions 82 and 84 with respect to one another. As shown in FIG. 4, the distal portions 84 of the antenna posts typically define notches 100, which are configured to facilitate suturing of antenna 28 and nitinol wire 29 (shown in FIGS. 2A-B) to the antenna posts.

Reference is now made to FIG. 5, which is a schematic illustration of stent 20, in accordance with some applications of the present invention. FIG. 5 shows a flattened profile of the stent, which depicts (for illustrative purposes) how the stent would appear if a longitudinal incision were to be made along the length of the stent at a given circumferential location of the stent, and the stent were to then be laid out flat upon a surface. Stent 20, in accordance with the applications shown in FIG. 5, comprises a generally cylindrical stent body 52 comprising a plurality of undulating strut rings 106. A distal-most undulating strut ring 108 comprises N distal-most-ring v-shaped strut pairs 110. A second undulating strut ring 112 is adjacent to distal-most undulating strut ring 108. Second undulating strut ring 112 comprises N/2 second-strut-ring v-shaped strut pairs 114. For some applications, N is an even integer that is greater than 9 and/or less than 15, e.g., 10-14. For example, FIG. 5 shows an application in which N is 12; thus, FIG. 5 shows 12 distal-most-ring strut pairs 110 and six second-ring strut pairs 114.

Stent 20 further comprises a plurality of antenna posts 46 protruding longitudinally from distal-most undulating strut ring 108, and a plurality of electrode posts 42 protruding from the distal-most undulating strut ring. Stent 20 typically comprises coupling elements 31, as described hereinabove, at a proximal end of the stent. Stent 20 further typically comprises coupling elements 40, as described hereinabove, for facilitating coupling of control capsule 30 to the stent.

For some applications, as shown in FIG. 5, each of distal-most-ring strut pairs 110 comprises two struts coupled at a respective proximal junction 116 of distal-most undulating strut ring 108. Adjacent distal-most-ring strut pairs 110 are coupled to one another at respective distal junctions 118 of distal-most undulating strut ring 108. Each strut 120 of each second-ring strut pair 114 is coupled to a respective proximal junction 116 of distal-most undulating strut ring 108, such as to define N/2 closed-cell arrangements 122 (e.g., N/2 closed diamond-shaped cells). Antenna posts 46 protrude longitudinally from respective distal junctions 118 of distal-most undulating strut ring 108, and electrode posts 42 protrude from respective proximal junctions 116 of distal-most undulating strut ring 108. The configuration of distal-most undulating strut ring 108 and second undulating strut ring 112, as described immediately above, typically helps stabilize the generally distal portion of stent 20. For example, the configuration of distal-most undulating strut ring 108 and second undulating strut ring 112 may help maintain antenna posts 46 and/or electrode posts 42 in a desired orientation (for example, such as to maintain antenna posts 46 and/or electrode posts 42 in alignment with a local longitudinal axis of the stent and/or of the blood vessel).

Typically, antenna 28, electrodes 22, and control capsule 30 are coupled to the stent, as described hereinabove. For some applications, each of electrode posts 42 protrudes from a respective one of a plurality of consecutive proximal junctions 116. For example, FIG. 5 shows four electrode posts 42 protruding from four consecutive proximal junctions 116. For some applications, stent 20 as shown in FIG. 3 is also shaped such that four electrode posts 42 protrude from four consecutive proximal junctions of the distal-most strut ring of the stent body. For some applications, as shown in FIG. 5, the number of antenna posts 46 is N/2, and each of antenna posts 46 protrudes from a respective distal junction 118 such that alternate distal junctions 118 have an antenna post 46 coupled thereto.

For some applications, as described above, N is an even integer that is greater than 9 and/or less than 15, e.g., 10-14. For example, for some applications, N is 12, as shown in FIG. 5. Thus, there are 12 proximal junctions 116, and consecutive electrode posts 42 (and hence, consecutive electrodes 22) are spaced from each other by approximately 1/12 of the circumference of the blood vessel, when stent 20 is an expanded state within the blood vessel.

As described hereinabove, typically, 3-5 electrodes (e.g., 4 electrodes) are coupled to stent 20 such that when the stent is placed inside the subject's aorta, the electrodes are placed in contact with the aorta at an aortic site as described hereinabove, and at circumferential locations that are between the 5 o'clock and the 1 o'clock positions (e.g., between the 7 o'clock and 12 o'clock positions). For some applications, stent 20 defines 3-5 electrode posts 42 (e.g., 4 electrode posts), the electrode posts being disposed around less than 75 percent, e.g., less than 50 percent, or less than 30 percent of the circumference of stent 20. Typically, a spacing of greater than 1/15 and/or less than 1/9 (e.g., 1/15- 1/9, e.g., approximately 1/12) of the circumference of the blood vessel is a preferred spacing of electrodes 22 with respect to each other.

Although some applications of the present invention have been described with respect to placing stent 20 inside a subject's aorta, the scope of the present invention includes placing stent 20 inside other blood vessels of a subject's body, e.g., the subject's carotid artery, pulmonary artery, and/or renal artery. For example, the stent may be placed in the renal artery, in order to treat renal dysfunction, and/or in the pulmonary artery, in order to treat pulmonary hypertension. Alternatively or additionally, the stent may be placed in the pulmonary artery and/or the carotid artery in order to be used for vagal stimulation (e.g., vasovagal stimulation), for example, in order to treat gastroesophageal reflux disease (GERD). Similarly, although the stent is shown at least partially disposed in the descending aorta, the scope of the present invention includes placing the stent at any location within the aorta, such as in the ascending aorta, the descending aorta, the aortic arch, or a combination thereof.

For some applications, the subject's cardiac cycle is determined by detecting an electrical signal from the subject's aorta, via electrodes 22, and deriving the subject's ECG and/or blood pressure from the electrical signal detected at the aorta, e.g., in accordance with techniques described in U.S. Ser. No. 12/792,227 to Gross (published as US 2010/0305392). For some applications, physiological parameters of the subject (such as the subject's cardiac cycle) are detecting using antenna 28, for example using techniques as described in US 2014/0180391 to Dagan, which is incorporated herein by reference. For some applications, electrical stimulation is applied to the aorta in coordination with the subject's cardiac cycle, based upon the signal detected at the aorta. For some applications, in response to detecting that a subject is undergoing an epileptic seizure, the subject's vagus nerve is stimulated by driving a current into the subject's aorta. For some applications, a current is driven into the subject's aorta in order to treat the subject for sleep apnea.

It is noted that, although some applications of the present invention have been described as being used in conjunction with a stent, the scope of the present invention includes applying the apparatus and methods described herein to a stent graft, mutatis mutandis. For example, an antenna may be coupled to the body of a stent graft via posts that longitudinally separate the antenna from a distal end of the body of the stent graft, in accordance with the techniques described hereinabove.

For some applications, the techniques described herein are practiced in combination with techniques described in WO 07/013065 to Gross, US 2009/0198097 to Gross, US 2010/0305392 to Gross, US 2011/0137370 to Gross, US 2012/0035679 to Dagan, and/or in US 2014/0180391 to Dagan, all of which applications are incorporated herein by reference.

It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof that are not in the prior art, which would occur to persons skilled in the art upon reading the foregoing description. 

1-28. (canceled)
 29. Apparatus for use with a tubular structure shaped to define a lumen thereof, the apparatus comprising: a stent configured to be placed in the lumen, the stent comprising: a generally cylindrical stent body comprising a plurality of struts; and a plurality of antenna posts protruding longitudinally from an end of the stent body, each of the antenna posts comprising: a proximal portion and a distal portion, each of which is configured to be generally straight in the absence of any force being applied to the antenna post; and a compliant junction disposed between the proximal portion and distal portion of the antenna post, the proximal portion and distal portion being configured to flex with respect to one another about the compliant junction; and an antenna disposed annularly on the distal portions of the antenna posts, such that the antenna posts separate the antenna from the end of the stent body.
 30. The apparatus according to claim 29, wherein the lumen of the tubular structure includes a lumen of a blood vessel of a subject, and wherein the stent is configured to be placed inside the lumen of subject's blood vessel.
 31. The apparatus according to claim 30, wherein the compliant junction is shaped to define a single sinusoidal wave.
 32. The apparatus according to claim 30, wherein the compliant junction is shaped to define 1.5 sinusoidal waves.
 33. The apparatus according to claim 30, wherein the compliant junction is shaped to define 2 or more sinusoidal waves.
 34. The apparatus according to claim 30, wherein the lumen of the blood vessel includes a lumen of a curved portion of an aorta of the subject, and wherein the stent is configured to be placed inside the lumen of the curved portion of the subject's aorta.
 35. The apparatus according to claim 34, wherein the compliant junction is configured to facilitate flexing of the distal portion of the antenna post with respect to the proximal portion of the antenna post, such that the post at least partially conforms with a curvature of the curved portion of the aorta even at an inner region of the curved portion of the aorta, at which a curvature of the curved portion of the aorta is greater than a curvature of an outer region of the curved portion of the aorta.
 36. The apparatus according to claim 35, further comprising a self-expandable wire that is coupled to the antenna, and that is configured self-expand inside the curved portion of the subject's aorta such as to bring the antenna into contact with an inner wall of the aorta, and wherein the compliant junction is configured to facilitate flexing of the distal portion of the antenna post with respect to the proximal portion of the antenna post, such that the antenna is brought into contact with the inner wall of the aorta even at the inner region of the curved portion of the aorta. 37-43. (canceled) 